If you're looking for anime similar to Detective Conan OVA 6: Follow the Vanished Diamond! Conan and Heiji vs Kid!, you might like these titles. All recommendations are made by Anime-Planet users like you!
Fudou Academy's Hajime Kindaichi is the grandson of the famous detective Kousuke Kindaichi. Though he often appears to be lazy in school and clumsy, he is actually a modern-day genius with an IQ of 180. Together with his childhood friend Miyuki, Hajime solves the most unsolvable murder mysteries with ease and grace. From missing students to wax museums, there's no case that Hajime Kindaichi can't solve!